Engine cylinder liner and method



July 20, 1943.

F. A. WAGNER ENGINE CYLINDER LINER AND METHOD Filed Julyfi, 1938 INVENTOR.

FREDER/C/(AWA GIVE/e B Y I v u ATTORNEY.

, properly conform itself to the true bore so as to Patented July 20,1943 2,324,541 ENGINECYLINDEB LINER AND METHOD Frederick A. Wagner,Oakland, Calif. Applicationluly 5, 1938, Serial No. 211,311

12 Claims. (Cl. 29-156.4)

This invention relates to internal combustion engines and has for itsobjects an improved liner for the cylinders of such engines as well asthe method of carrying out the invention. This application forms acontinuation in part of thy copending application forpatent filed underSerial No. 98,942 on September 1, 1936.

One of the objects of the invention is to pro vide a wear-resistingsegmental cylindrical liner for internal combustion engine cylinders ofrel-r m atively thin, flexible sheet metal for forcibly pressing iiito atrue cylinder bore to fit tightly therein without requiring auxiliaryfastening means, and'which by reason of its flexibility will 15 require,if anything, but very little grinding to finish the interior surface tothe exact surface and dimensions required.

Another object is to produce acylinder liner of the kind above describedfrom rolled or drawn 'sheet metal thereby eliminating machine work inthe preparation of the liners. 1

Another object is to provide a sheet metal liner of this kind which isformed in at least two seg ments of a cylinder and which, when placed inabutting relation, will tightly fit within the true bore of the cylinderto be lined.

Other objects and advantages of the invention will appear in thefollowing description and 'accompanying drawing.

In the drawing: Figure 1 is, an elevation of the forming die with aliner segment in place.

Figure 2 is a perspective view showing two'segments or halves of theshaped liner placed with edges in abutting .relationto form a completecylindrical liner ready for press-forcing into a suitably bored outcylinder. Figure 3 is a vertical cross section of a cylinden of aninternal combustion engine with the segmented thin sheet'metal linetightly fitting in place. Figure 4 shows the lower end of a pressmandrel with reduced end to fit within the liner when forcing in place.j Before describing the invention in detail, it is desired to state thatthe lining of engine cylinders by inserting sleeves .of various metalsto form an interior lining for the cylinder is well known in the art,but such sleeves have generally been. of two types; first, made ofcomparatively thick metal, such as castings of bronze or special ironwhich were carefully machined both inside and out and thereafter fittedinto the engine cylinder, sometim'es'by first heating the cylit anyappreciable inderto expand the cylinder so that it would shrink tightlyupon the sleeve liner after insertion,secondly, sleeves have been madeof thin metal and fitted into the cylinders by shrinking 5 as abovedescribed, or by forcibly expanding the sleeve within the cylinder byrolling the sleeve internally until in tightcontact withwater c han-,neled cylinder walls to form the inner wall of the water or steamjacket, as inPatent No.,240,'l08. However, for engine cylinders suchthin metal liners were generally in the complete cylindrical form whichis extremely diflicult to produce accurately in a, thin, metaksleeve,and whilein' some cases it hasbeenpurposed toroll thin,

cylindrical liners tolcomplete cylindrical form either with or without awelded joint, the making of such liners for use in engine cylindersentails such precise work'to insure the exact dimensions, required forboth external as well as internal diameters while at the same timepreserving proper curvature,that it has never come into use inautomotive engines, though hundreds of thousands of engine cylinders arebored out every year and over-size pistons must be put in to, compensatefor the metal removed. H As a practical automotive machinist doing a.great deal of enginecylinder reboring, I have experimented with varioustypes of liners in an endeavor to avoid the requirement for over-sizepistons in the rebored cylinders, particularly with the rolling ofcomplete cylindrical sleeves formed a of a sheet of steel with welded orunwelded abutting ends and with the inner surface of the formed sleevehardened as by the nitriding, or

carburizing methods and as set out in my copending patent applicationabove mentioned.

However, in practical application, I found that the work of forming theliners of sheet steel could be carried out with much greater accuracyand in a fraction of the time, if two half cylinders were formedseparately, either by rolling, or

preferably in a pairof dies, and then the two halves abutted on theirlongitudinal edges and forced into therebored engine cylinder with apress, and greatly tomy surprise, I found that such liners of thin sheetsteel, though unsecured in place except by friction,'have shown notendency to become loose or displaced after many thousands of miles ofuse in automobile truck service, yet after prolonged usage when wearfinally' does take place they may be forcibly pushed or pulled out ofthe cylinder again and a/ new set pushed in.

At this point I wish to say that I am aware of thick rigid splitbushings as used in split and solid pulley bores and machine bores, alsoaware of thin sheet 'metal split bushings having been applied to shaftbearings, but in such bearings the shell or housing is itself split, andthe two halves inserted and the housing cap clamped over the bushing,something which cannot be done with an internal combustion enginecylinder where the cylinders are always cast solid or. integrally.

In carrying out my invention, I rebore the worn cylinder sufiiciently toallow for the thickness of the sheet metal liner which is going to beinserted,'so as to re-establish the original bore, to fit the originalsized'pistons, or to make it slightly less in diameter after lining if aslight cut is required oil of the pistons to true them up. I then cuttwo sheets of the desired rolled or drawn thin sheet steel or otherwear-resisting sheet metal, 01 a proper size each to form at least afull half cylinder for the required liner, and then shape themseparately to half cylinder form with the rolled grain of the sheetrunning crosswise or rather circumferentially of the bore of thecylinder. v

The forming or shaping of the sheet metal to half cylinders may be doneby passing through forming rolls, but in which case the metal sheetshould be somewhat longer than required to form v a half cylinder toallow for the imperfectly rolled or curved end margins of the sheetto'be cut oil. Instead of rolling the sheets, I'prefer to press them toshape between a pair of dies, I, 2, as shown in Figure 1, and in whichthe half cylindrical sheet metal liner is indicated at 3.

The thin sheet metal, if of a springy nature, will tend to open outsomewhat when released from the dies, but will assume the proper curvewhen forced into the cylinder, though if the metal is very springy andopens out too much, it may be given successive blows between a pair ofdies of somewhat less than the desired curvature while successivelyarcuately advancing the sheet to lutely tight abutting Joint when thelining is in place in the cylinder, as the sheetmetal frequentlystretches unequally in rolling or die shaping, and this feature of themethod of forming thin sheet metal liners is important for perfectresults whether the cylindrical ously been done by rolling or shapinghas previdie pressing.

, If any heat treating .or hardening or toughening or other treatment ofthe inner surface of thin sheet steel liners is desired, or suchtreatment as nitriding, or carburizing followed by hardening the finaledging to: determine exact size of the shells and insure straight, true,meeting edges as above explained should be carried out after anyhardening or heat treating of the shell, as some steel shrinks 'orexpands in the treatment and might otherwise not fit in the boredcylinder.

Also, particularly if the shell segments are hardened by any process, orthe sheet metal used is relatively hard, it is desirable that th'e outersurface be relatively soft or left in its normal unhardened condition toinsure a better frictional and thermal contact with the bore of thecylinder to respectively prevent possible displacement and to dissipateheat. To better carry out-the above the outer surface of the shells mayfirst be plated or coated with a protective layer of a softer metal,such as copper, zinc, tin, or other soft metal. Such a plating ispreferably applied to one side of the flat sheets of metal beforeshaping into cylindrical form, but any hardening if re-. sorted to, ispreferably carried out after shaping,

for otherwise the shaping is made more dimcult if not impossible tocarry out without injury to the interior surface. In case of nitriding,or carburizing the sheets with subsequent hardening, such platingconfines the action to the inner surface only of the sheets. Copper ispreferred as the rear plating metal for the liner as itssoftness insuresa good thermal contact with the bored cylinder walls, and its highthermal conductivity is important to pass the heat outward from thebring the pressure of the dies at all points from end to end of thesheet, paying particular attention to the ends of the sheet which willabut, as the curvature should be substantially correct ad.- jacent theseends as they do not flex so readily as the intermediate portions of thesheet.

As it is necessary that the longitudinal edgesof the two halves meet intightly abutting relation when the lining is in the cylinder, while atthe same time the body of the liner must seat perfectly against theinner wall of the rebored engine cylinder, the precise circumference orlength (arcuately) of the two segments is of greatest importance, for iftoo long the liner cannot seat against the wall of the cylinder, and iftoo short it will not stay in place. To therefore insure the arcuatelength of each segment being correct, they may be made a trifle too longand clamped in the dies shown in Figure 1, either separately or placedend to end if the dies are long enough, and a slight finishing cut orgrind taken off of the upper edge or edges 4 of the liner-the formingdies or a special set being made of a suitable depth to permit ,this.

When relining several duplicate cylinders, a pair of narrower strips ofthe same sheet of lining metal may be formed in the die and firstfinished on the edges as described and tried out in one of the cylindersto determine its fit before edge finishing of the full length segments.

Such a final edging or finishing also insures the edges being straightand true, and an absoliner to the cylinder walls and water jacket orcoolingfins.

In shaping the half shells or segments of the lining they normally tendto spring outward again to a somewhat larger radius curve than that ofthe cylinder, though if the extreme ends or abutting margins of thesheets are substantially to the curve of the cylinder, and the length iscorrect, a snug fit against the walls of the cylinder will be assured,as the sheet metal being flexible, the

pressure of its abutting edges will force all portions in perfectcontact with the cylinder bore.

In Figure 3 the two segments 3, 3 of my thin sheet metal liner are shownin place in a conventional engine cylinder 8, and is applicable'to anykind of an internal combustion engine cylinder whether water or aircooled. One of the,

abutting joints of the liner ends is shown at 9 in this figure.

While I have mentioned my thin sheet metal liners as applied toreboredengine cylinders to compensate for the metal removed, the use of theinvention goes 'far beyond this, and it is contemplated that allinternal combustion engine cylinders in the future be originally boredout of a size to be initially fitted with such a thin flexible sheetmetal split liner of definite thickness, say 3 2', 1 s, or of an inch inthickness, and after this becomes worn from long use, it may be pushedor pulled out and a new pair of shells pushed in, thus forever entirelyavoiding any reboring of the cylinder, and giving the cylinder ure 4)may be ner surface to v slide over it as the assess? unlimited life byrepetition of this simple procedure. v A

In pressing the lining in place, the two shells 3, are assembled asshown in Figure 2, and one or more external clamping straps 1 areclamped about them to hold them together for forcing into the cylinder.A lubricant is first wiped around the inside of the cylinder wall aswell as on the interior surface of the clamps, and on the exterior ofthe lining. The upper edge of the cylinder may be rounded slightly tofacilitate entry of the liner, and if the linings are of very thinmetal, an internal supporting mandrel or reduced extension 6' of thepress mandrel I (Figusedto insure against inward buckling particularlyat the abutting edges. After the lining shells are seated in place, avery light finishing grind may be taken on of the inremove slightinequalities on the surface of the liner, if desired, but which will notbe required if properly surfaced sheet metal is used. a

In applying the pressure on the assembled and clamped shells, the shellsmay be forced through the lubricated clamps or straps without releasingthe straps until necessary to push the remaining portion of the shellsinto the cylinder, though if the press mandrel 6 be no larger than theoutside diameter of the liner, the clamp or clamps will mandreldescends.

While my invention is principally directed to the use of thin sheetsteel, inner surface hardened, or otherwise treated, liners to resistwear in engine cylinders, it should be noted that considerableexperimentation is now being carried on by engine builders to determinewhether or not the combined heat and chemical action of the .explodinggases are equally or more responsible for destruction of the wallsof'engine cylinders, and if so what steels or other alloys will bestresist such deleterious actions. Therefore, when the best resistantmetal is finally decided by the result of all these experiments, myinvention affords the best means of carrying the use of such metal intopractice, especially if all engines are initially factory equipped withmy liners made of thin corrosion-resisting metal, be it stainless steelor anyother metal or alloy, so thatthey' merely required renewal afterlong periods of use, thus doing away forever with the reboring ofinternal combustion engine cylinders.

While I have found by thousands of miles of tests of engines lined by mymethod above described that no positive securing-of the liners in placeinthe cylinders is required, still the, invention in its broader aspectdoes not preclude any desired fastening means being employed if desired,or the use of a slight shoulder at the lower or inner'end of thecylinder to positively insure.

no possible creeping of the linerin that direction,

as is positively insured in the opposite direction by the head of thecylinder when in place, though linings of various kinds,

. grain of the sheet metal minute striations in the plained for the twosegments. and they also remain firmly locked into place without securingmeans and do not become displaced in use. The use of three segments isan advantage if heat -treating is used as it is easier to treat smaller.

areas without buckling.

In considering theabove disclosure it should be noted that thepreforming of the thin flexible sheet liner segments to exact size tosecure the proper fit is one of the important features of the invention.That the invention is confined strict- 1y to a flexible sheet metalliner for a cylinder of an internal combustion engine or similar pistonworking barrel, and the method of applying it, that the problem involvedhas no relation to bushings used in pulleys, bearings, or brake bandhave not reduced the daily reboring of many thousands of enginecylinders one bit, that by the use of my'invention it is possible togain the advantages of accurately rolled toughness and density,-togetherwith accuracy-of gage and finish of such sheet 'metalimpossible to getin a cast liner, or any form of drawn or extruded metal tubing so thanthis, it permits placing the natural or rolled transversely to therecip-i rocating nfovement of the engine piston. to thereby effectuallyovercome grooving due to possible metal-advantages not possible toobtain with drawn metal tubing.

-'In view of the above, I. therefore feel entitled to patent coverage onmy invention or any modification thereof when applied to the cylindersof an internal combustion engine, as may come within the scope of myappended claims.

I therefore claim:

1. The method of lining an tion engine cylinder having a true bore,which comprises forming sheets of thin flexible metal of uniformthickness into a plurality of duplicate longitudinal straight-edgedsegments of-a cylinder with all longitudinal edges parallel to the axisof the cylinder and of a size to form when assembled with longitudinaledges abutting a completecylindrlcal sleeve of a size to 2. The methodof lining an internal OOmbUS- tion engine cylinder having atrue bore,which comprises forming sheets of thin flexible metal of uniformthickness into a plurality of duplicate'longitudinalstraight-edgedsegments of a :zlinder with all longitudinal edgesparallel to f e axis. of the cylinder and of a size to form whenassembled with longitudinal edges abutit may be stated that thin sheetmetal linings ap plied according to my invention require consid-y willbe relieved so that it may easily be ,removed.

Also to be noted is, that while I show and prefer my cylindrical linerto be made of two equal 1 half segments, it is not limited to this as Ihave found it possible, especially inlarge bore cylinders, to use threesegments, pressed in as exting a complete cylindrical sleeve of a size'to form a press fit within the engine cylinder, as- 1 sembling thesegments into such cylindrical form with edges abutting substantiallythroughout ther length and unattached, and thereafter simultaneouslyforcing the thus assembled unattached segments longitudinally andtightly into the cylinder while supporting the segments interiorlyagainst inward buckling,

3. The method of lining an internal combustion engine cylinder having atrue bore, which comprises forming sheets of thin flexible metal ofuniform thickness into a plurality of duplias any and all of these stripsheet steel or special alloys, with the greater homogeneity,

far obtainable, and more internal combusc ate longitudinalstraight-edged segments of a cylinder with all longitudinal edgesparallel to the axis of the cylinder and of a size to formwhen assembledwith longitudinal edges abutting a complete cylindrical sleeve of a sizeto form a press fit within the engine cylinder, assembling the segmentsinto such cylindrical from with edges abutting substantially throughouttheir length and unattached, and thereafter simultaneously forcing thethus assembled unattached segments longitudinally and tightly into thecylinder while supporting the segments inter'iorly in a manner to assurealignment of their edges while entering the cylinder.

4. The method of lining an internal combustio engine cylinder having atrue bore, which comprises forming sheets of thin flexible metal ofuniform thickness into a plurality of duplicate longitudinalstraight-edged segments of a cylinder with all longitudinal edgesparallel to the axis of the cylinder and of a size to form whenassembled with longitudinal edges abutting'a complete'cylindrical sleeveof a size to form a press fit within'the engine cylinder, assembling thesegments into such cylindrical form with edges abutting substantiallythroughout their length and unattached, clamping the assembled segmentstogether to bring them to substantially true cylindrical form, andthereafter simultaneously forcing the thus assembled unattached segmentslongitudinally and tightly into the cylinder.

5. The method of lining an internal combustion engine cylinder having atrue bore, which comprises forming sheets of thin flexible metal ofuniform thickness into a plurality of duplicate longitudinalstraigt-edged segments of a cylinder with all longitudinal edgesparallel to the axis of the cylinder and of a size to form whenassembled with longitudinal edges abutting a complete cylindrical sleeveof a size to form' a.

press fit within the engine cylinder, assembling the segments into suchcylindrical form with edges abutting substantially throughout theirlength and unattached, clamping the assembled segments together to bringthem to substantially true cylindrical form, and thereaftersimultaneously forcing the thus assembled unattached segmentslongitudinally and tightly into the cylinder while sliding them throughthe clamping means. 7

6. An internal combustion engine cylinder provided with a true borelined with a sheet metal liner composed of a plurality of duplicate andsymmetrical longitudinal cylindrical segments of thin flexible sheetmetal of uniform thickness longitudinally press fitted into place andwith lcngituriinally straight edges in unattached abutltitilii iiextending parallel tn the longituti axis of the cylinder. An internalcombustion engine cylinder presided with a true bore lined with a sheetmetal liner composed of a plurality of duplicate and symmetricallongitudinal cylindrical segments of thin flexible sheet metal ofuniform thickness longitudinally press fitted into place and withlongitudinal straight edges in unattached abutting relation extendingparallel to the longitudinal axis of the cylinder, said segments backedwith a uniform thin coating of relatively soft metal providing increasedfrictional resistance against displacement in use.

8. An internal combustion engine cylinder provided with a true borelined with a sheet metal iiner'composed of a plurality of duplicate .andsymmetrical longitudinal cylindrical segments of thin flexible sheetmetal of uniform thickness longitudinally press fitted into place andwith longitudinal straight edges in unattached abutting relationextending parallel to the longitudinal axis of the cylinder, saidsegments backed with a uniform thin coating of copper providingincreased thermal transmission and frictional resistance againstdisplacement in use.

9. A piston cylinder lined internally with a sheet metal liner formed ofthin flexible sheet metal of uniform thickness with longitudinallystraight edges in unattached abutting relation press fitted into place,the grain of said sheet metal extending circumferentially of thecylinder.

10. A sheet metal wearing liner for a piston cylnder comprising aplurality of duplicate longitudinal cylindrical segments of thinflexible sheet metal of uniform thickness with longitudinal edgesstraight and parallel to the axis of the cylinder, the segments being ofsuch a size that when assembled in cylindrical form with edges abuttingthey form a complete cylidrical liner of a size adapted for longitudinalpress fitting into the cylinder for tightly seating therein againstdisplacement in use.

11. A sheet metal wearing liner for a piston cylinder comprising twohalf cylindrical segments of thin flexible sheet metal of uniformthickness with longitudinal edges straight and parallel to the axis ofthe cylinder, the segments being of such a size that when assembled incylindrical form with edges abutting they form a complete cylindricalliner of a size adapted for longitudinal press fitting into the cylinderfor tightly seating therein against displacement in when assembled incylindrical form with edges abutting they form a complete cylindricalliner of a size adapted for longitudinal press fitting into the cylinderfor tightly seating therein against displacement in use, the grain ofsaid sheet metal extending circumferentially of the liner.

FREDERICK A. WAGNER.

